Eliminate unwanted background noise with the Shure 522. This cardioid mic is
designed to suppress the noise that can be generated by dispatchers working
nearby, ventilating equipment, office machines, feedback from PA paging
applications and much, much more.

Shure 522 Features Include:

Dual impedance(19 to 300 ohms or High)

lmpedance change switch for convenient change-over

Finger-tip control bar (locking or non-locking action) to actuate
microphone circuit and an external relay or control circuit